Responses to Rare Visual Target and Distractor Stimuli Using Event-Related fMRI

Abstract

Previous studies have found that the P300 or P3 event-related potential (ERP) component is useful in the diagnosis and treatment of many disorders that influence CNS function. However, the anatomic locations of brain regions involved in this response are not precisely known. In the present event-related functional magnetic resonance imaging (fMRI) study, methods of stimulus presentation, data acquisition, and data analysis were optimized for the detection of brain activity in response to stimuli presented in the three-stimulus oddball task. This paradigm involves the interleaved, pseudorandom presentation of single block-letter target and distractor stimuli that previously were found to generate the P3b and P3a ERP subcomponents, respectively, and frequent standard stimuli. Target stimuli evoked fMRI signal increases in multiple brain regions including the thalamus, the bilateral cerebellum, and the occipital-temporal cortex as well as bilateral superior, medial, inferior frontal, inferior parietal, superior temporal, precentral, postcentral, cingulate, insular, left middle temporal, and right middle frontal gyri. Distractor stimuli evoked an fMRI signal change bilaterally in inferior anterior cingulate, medial frontal, inferior frontal, and right superior frontal gyri, with additional activity in bilateral inferior parietal lobules, lateral cerebellar hemispheres and vermis, and left fusiform, middle occipital, and superior temporal gyri. Significant variation in the amplitude and polarity of distractor-evoked activity was observed across stimulus repetitions. No overlap was observed between target- and distractor-evoked activity. These event-related fMRI results shed light on the anatomy of responses to target and distractor stimuli that have proven useful in many ERP studies of healthy and clinically impaired populations.

Emotion?attention network interactions during a visual oddball task

“…The dorsal frontoparietal regions engaged by attentional targets in the present study are consistent with those reported in previous oddball tasks [4,8,9,25,35,49]. Furthermore, we show here that these dorsal regions respond to task-relevant oddball stimuli similarly despite variations in their emotional properties.…”

“…Finally, we test whether the oddball response in dorsal brain regions is invariant to emotional content. Because dorsal frontoparietal cortex is consistently activated in oddball tasks that have used a variety of target stimuli [8,9,25,35,49], we expect to see similar activity in these regions across the two experimental groups.…”

The hemodynamics of oddball processing during single-tone and two-tone target detection tasks

“…ERP source localization studies suggest that the P3 is localized to the bilateral prefrontal cortex, parietal-occipital junction, and parietal lobe, while the N1 is localized predominantly to bilateral auditory cortex, with some evidence supporting additional sources in the prefrontal cortex (Anderer et al, 1998;Giard et al, 1994;Halgren et al, 1995a;Liegeois-Chauvel et al, 1994). Functional magnetic resonance imaging (fMRI) studies have confirmed and extended these findings Casey et al, 2001;Clark et al, 2001;Clark et al, 2000;Kiehl et al, 2001a;Kiehl et al, 2001b;Kiehl & Liddle, 2003;Kiehl et al, 2005;Kirino et al, 2000;Linden et al, 1999;McCarthy et al, 1997;Menon et al, 1997;Opitz et al, 1999;Stevens et al, in press;Strange & Dolan, 2001). These studies report that target detection elicits widespread cortical and subcortical activation, including multiple foci in the prefrontal, temporal, parietal and occipital lobes, and subcortical sites.…”

Effects of modafinil and bromazepam on decision-making: a P300 analysis

“…Greater latency for the target condition was observed in this study. Such finding seems to be related to the fact of this stimulus appearing less frequently than the non-target stimulus, therefore causing a delay in the sensorimotor integration process, which is common in the presence of a rare stimulus [27]. In addition to this, the lower P300 latency for the non-target condition may be associated to the fact of the subjects having to inhibit their motor response (i. e., press the joystick).…”

“…During task execution, the subjects were instructed to present a motor response only when the target stimulus appeared on the computer screen. Such process required decision making [27,34]. Studies show that this finding is commonly observed during an active stimulus, since the processing of a passive and more frequent stimulus produces lower P300 amplitude, due to the fact of the task involving simplified attention strategies for amplitude reduction [7].…”